1. Field of the Invention
This invention relates to apparatus for removing cut panels from sheet material and more particularly, to apparatus for removing cut panels in an endless web in the production of window envelopes.
2. Description of the Prior Art
In envelope making machines, the window openings are cut in a continuous web or in individual envelope blanks that are conveyed between a rotary type window or panel cutter and a backing anvil. Frequently, the cutting operation is such that the panel or chip is not completely separated at the cut edges and this is especially true when the cutting die is slightly worn. Thus, frequently the panel or chip is incompletely separated and the uncut panel or chip must be physically removed from the window openings.
In the past, several arrangements were provided to remove the panel or chip from the web or envelope blank. In one arrangement, as is illustrated in U.S. Pat. No. 3,186,274, the panels were removed by means of pins mounted on a roller that would pierce the panel and remove the panel from the web or envelope blank. Problems were encountered with the pin arrangement in that the pins were frequently broken when the envelope machine was operated at high speed to render the panel removal apparatus inoperative.
Also, other arrangements, such as gripper fingers have been used. The same disadvantages, however, are present with the gripper fingers. Both suction and air under pressure have been utilized with the rotating roller to secure the panel or chip to the roller and to positively discharge the panel from the roller. This type of panel removal apparatus increases the cost of the dies and the valve assemblies to provide the suction and air under pressure. Further, the valves generate heat and require changing when the roller is changed during an envelope size change. Other panel removing devices are disclosed in U.S. Pat. Nos. 1,007,856; 1,290,301; 1,614,488 and 3,103,842.
There is a need for simple, inexpensive apparatus to positively remove the panels or chips from the web or envelope blank that is operable at high speeds.